integrate connection.terminate() for supporting dialects

Integrated support for asyncpg's ``terminate()`` method call for cases
where the connection pool is recycling a possibly timed-out connection,
where a connection is being garbage collected that wasn't gracefully
closed, as well as when the connection has been invalidated. This allows
asyncpg to abandon the connection without waiting for a response that may
incur long timeouts.

Fixes: #8419
Change-Id: Ia575af779d5733b483a72dff3690b8bbbad2bb05

1 files changed, 21 insertions, 0 deletions

diff --git a/lib/sqlalchemy/engine/interfaces.py b/lib/sqlalchemy/engine/interfaces.py
index 778c07592..01b266d68 100644
--- a/lib/sqlalchemy/engine/interfaces.py
+++ b/lib/sqlalchemy/engine/interfaces.py
@@ -966,6 +966,10 @@ class Dialect(EventTarget):
     is_async: bool
     """Whether or not this dialect is intended for asyncio use."""
 
+    has_terminate: bool
+    """Whether or not this dialect has a separate "terminate" implementation
+    that does not block or require awaiting."""
+
     engine_config_types: Mapping[str, Any]
     """a mapping of string keys that can be in an engine config linked to
     type conversion functions.
@@ -1784,6 +1788,23 @@ class Dialect(EventTarget):
 
         raise NotImplementedError()
 
+    def do_terminate(self, dbapi_connection: DBAPIConnection) -> None:
+        """Provide an implementation of ``connection.close()`` that tries as
+        much as possible to not block, given a DBAPI
+        connection.
+
+        In the vast majority of cases this just calls .close(), however
+        for some asyncio dialects may call upon different API features.
+
+        This hook is called by the :class:`_pool.Pool`
+        when a connection is being recycled or has been invalidated.
+
+        .. versionadded:: 1.4.41
+
+        """
+
+        raise NotImplementedError()
+
     def do_close(self, dbapi_connection: DBAPIConnection) -> None:
         """Provide an implementation of ``connection.close()``, given a DBAPI
         connection.